Jose P. Ruiz

Electrochemistry of some β‐Substituted Polythiophenes Anodic Oxidation, Electrochromism, and Electrochemical Deactivation

The anodic electrochemistry of the soluble poly(3-ethylmercaptothiophene) (PEMT) and poly[3,4-bis(ethylmercapto)thiophene] (PBEMT), is compared with the behavior of polythiophene (PT), poly(3-methylthiophene) (PMT), and poly(3-hexylthiophene) (PHT). In all five cases, the first anodic oxidation was reversible and was accompanied by reversible electrochromic behavior. When the polymers were driven to more positive potentials, there was immediate loss of electroactivity and concomitant color change to black. An electrochemical cross-linking/chain extension technique is discussed for PEMT as a means of growing smooth polymer films on electrode substrates starting from soluble oligomers in solution

Optical Absorption, Luminescence, And Redox Switching Properties Of Polyphenylene Derivatives

A series of polyphenylene derivative polymers with a variety of heterocyclic units along the main chain, and various pendant groups, have been synthesized and their optoelectrochemical properties examined. Polyphenylenes containing electronically isolated emitter centers have optical absorption and luminescence characteristics which are a function of the length of the conjugated unit. A water soluble electroactive rigid-rod poly (p-phenylene), specifically Poly[2,5-bis (propoxy-3-sulfonate)-1,4-phenylene- alt ,4-phenylene], has been prepared. Solution cast films of this polymer exhibit optical evidence for bipolarons via both p-type and n-type electrochemical doping. Further poly ( p -phenylene) (PPP) derivatives are being pursued, including PPPs bearing pendant donor molecules for charge transfer complex formation. A series of polymers containing alternating p-phenylene units with bithienylene and bifuranylene units, specifically poly[1,4-bis (2-heterocycle)-2,5-disubstituted-1,4-phenylenes], have been synthesized with both alkyl and alkoxy pendant groups. Steric interactions disrupt the ability of the redox doped polymers to attain planarity, strongly affecting the polymers oxidation potentials and DC conductivities. The substituent length has little effect on the electronic properties of the polymer, but greatly affects the polymers solubility and transport properties during redox switching.

Borane and monoiodoborane derivatives of some bis(diphenylphosphino)alkanes

Abstract A series of borane and monoiodoborane derivatives of bis(diphenylphosphino)alkanes. (C6H5)2P (CH2)nP(C6H5)2 in which n has values of 2 through 4 has been synthesized. Only compounds with the formulae [(C6H5)2P]2(CH2)n · (BH3)2 and (C6H5)2P]2CH2)n · BH2I were isolable, the latter being boronium iodides. The compounds were characterized by their melting points, elemental analyses, molar conductivities, infrared spectroscopy, and 1H and 11B nuclear magnetic resonance spectroscopy. The relationship between the length of the carbon chain and the 11B NMR chemical shift is discussed.

The effect of structural modification on the physical and electronic properties of polythiophenes

Abstract Conductive polymers of β-ethylmercapto substituted thiophenes have been synthesized to obtain soluble materials. Structural analyses of the conducting polymers indicate that a well-defined β-substituted 2,5-thienylene polymeric structure is formed. Electronic absorption spectra of oxidized polymer films or solutions exhibit formation of bipolaronic species. Conductivities in the semiconductor range have been obtained for the oxidized polymers. Theoretical calculations have been carried out, using PRDDO method, to demonstrate radicalion reactivities for the thiophene monomers and minimum conformations for substituted polymers. Heterogeneous blends have been made by co-casting these polymers with typical thermoplastic materials and studied by optical microscopy and thermal analysis.

Electrically conducting polymers containing substituted phenylene and heterocycle repeat units

Abstract A series of polymers containing alternating biheterocycle and p -phenylene repeat units has been synthesized and studied. When the heterocyclic unit is thiophene, the materials demonstrate electrochemical properties similar to those found for polythiophenes and retain the synthetic flexibility for substitution found in phenylene compounds. The monomers were substituted at the 2- and 5-positions of the phenylene ring with methyl, methoxy, heptoxy, dodecyloxy and hexyl groups. The electronic properties were found to depend on both the electron donating ability and the steric effects of the substituents. PRDDO and ab initio calculations were carried out to correlate the molecular structure with the observed electronic properties. Optoelectrochemical and solution doping results revealed the presence of bipolaron species in the oxidized state and the optical band gap was compared with extended Huckel calculations. The monomers and polymers were characterized using a variety of FT-NMR and FT-IR techniques.

Electroactive and soluble polyheterocycles and transition metal complex polymers

Abstract We have employed three different methods to obtain soluble electroactive polymers. A series of pendant substituted polythiophenes have been prepared and studied, using various ethylmercapto and alkyl substituents. Results of electrical conductivity, optical spectroscopy and theoretical modeling will be presented. N-propane sulfonate substituted pyrrole has been polymerized to yield water soluble, self-doped polymers. Electrochemical analyses show these materials, as copolymers with pyrrole, to behave as cation specific membranes. Charged transition metal bisdithiolene linkages have been incorporated into polymer main chains, along with flexible linkages, by utilizing the ionic ligand derived from bis-(4-styryldithiocarbonate) oxide. In solution the polymers have electrochemical characteristics comparable to transition metal bisdithiolenes.

A Challenging Diagnosis of Ascites: A Case Report of Peritoneal Tuberculosis

Approximately 2 billion people, which is about one third of the worlds population, are infected with tuberculosis (TB). Around 10% of infected people will develop active TB at one point in their lifetime. We present a rare case of a 68-year-old male who presented to the emergency department with a 2-week progressive dyspnea. In addition, the patient complained of generalized weakness, subjective fevers, and abdominal pain in the right upper quadrant. Ascites was noted on physical exam, and the patient underwent a diagnostic paracentesis with initial workup that was unrevealing for underlying etiology. Abdominal computed tomography was done, which revealed peritoneal carcinomatosis. He underwent omental biopsy which showed necrotizing granulomatous inflammation with rare acid-fast bacilli. Repeat biopsy was culture positive for mycobacterium tuberculosis complex. The patient was started on rifampin, isoniazid, pyrazinamide, and ethambutol with improvement of his symptoms days after treatment was started. This case demonstrates how the diagnosis of peritoneal tuberculosis can be elusive. Physicians must be aware of this disease and its behavior in high risk patients, also of the current diagnostic limitations.